Method for fibrillating a transversely oriented plastic material

ABSTRACT

Method for fibrillating transversely oriented plastic material by moving the material in the direction of its length at a given speed and instantaneously and simultaneously applying compressive forces and longitudinal forces to the material while maintaining the speed at which it is moving to split the material into a web of interconnected fibers.

is United States atent 1 3,659,765 Kalwaites 1 May 2, 1972 54] METHODFOR FIBRILLATING A [56] References Clted N VE ELY ORIENTED PLASTIC TRA SRS UNITED STATES PATENTS MATERIAL 3,424,358 1 1969 R b' t l .225 3 [72]F'ank Kalwaies somerv'ue' 3 427 654 21969 1125:5552: "225% [73]Assignee: Johnson & Johnson Primary ExaminerFrank T. Yost [22] Filed:1969 At!0rneyRobert L. Minier, John H. Trcgoning and Alex- 21 Appl. No.:870,877 anderT- Kardos Related US. Application Data [57] ABSTRACTDivision 0f 1963, Method for fibrillating transversely oriented plasticmaterial by moving the material in the direction of its length at agiven speed and instantaneously and simultaneously applying com- 225/4,28/D]G- 225/93 pressive forces and longitudinal forces to the materialwhile [51] Int. Cl. ..B26f 3/02 maintaining the Speed at which it ismoving to split the d. [58] Field of Search ..225/1, 3, 4, 2, 93, 96,97; a] into a b ofimerconnected fib 1 Claims, 2 Drawing Figures PatentedMay 2, 1972 INVEN'I'OR Fxawvm flu nan-:5

ATTORNEY METHOD FOR FIBRILLATING A TRANSVERSELY ORIENTED PLASTICMATERIAL This is a division of application Ser. No. 7 l0,6l l, filedMar. 5,1968 now U.S. Pt. No. 2,515,325.

This invention relates to a method and apparatus for fibrillatingtransversely oriented plastic films to produce split fiber webs.

It is known that when films are highly oriented; i.e., up to fiber typeorientations, that when forces are applied to these films they can bedisrupted into fibrous type networks. By fiber type orientation it ismeant that the fiber has a high degree of parallel orientation in onedirection and very little strength perpendicular to that direction. Theproblems splitting such oriented films has been that to disrupt thesehighly oriented films and produce a fiber network the forces fordisruption must be applied uniformly over the entire film area andforces must be such that they do not completely tear the film and merelyproduce shreds. The forces must be applied over very small incrementalareas of the film and they must be applied uniformly over the entirearea of the film.

In accordance with the present invention I have discovered a method forapplying these forces uniformly over the entire areas of the film andover very small incremental portions along the length of the film toproduce a uniformly fibrillated web.

In accordance with the method of the present invention a transverselyoriented film is moved continuously in its longitudinal direction. Thefilm is moved at a given and controlled speed. Simultaneously,instantaneous compressive and longitudinal forces are applied to thefilm while maintaining the speed of the film at its given speed. Theseforces uniformly fibrillate the film into a web of interconnectedfibers.

Apparatus for carrying out the method of the present invention comprisesa pair of rotatable rolls positioned adjacent each other with their axisparallel to form a nip. The transversely oriented film is passed in itslongitudinal direction through this nip. One of the rolls of the nip isnon-resilient while the other roll is resilient. The non-resilient rollrotates at a given speed. In contact with the surface of thisnon-resilient roll immediately adjacent the input side of the nip is ablade. The blade contacts the surface of the roll along a line parallelto the axis of the roll. As the film is fed under the blade, the bladeforces the film onto the surface of the non-resilient roll so that thefilm has the speed of the non-resilient roll as the film passes throughthe nip. The other roll is resilient and is pressed against thenon-resilient roll. The resilient roll is rotated at a faster peripherallinear speed than the nonresilient roll. The resilient roll applies bothcompressive and longitudinal forces to the transversely oriented film asthe film passes through the nip and fibrillates it into a web ofinterconnected fibers.

The invention will be more fully described when taken in conjunctionwith the accompanying drawings wherein:

FIG. 1 is a side elevational view of the apparatus for carrying out themethod ofthe present invention;

FIG. 2 is an enlarged cross-sectional view of the apparatus forinstantaneously and simultaneously applying compressive and longitudinalforces to the transversely oriented film.

The films which may be utilized in accordance with the present inventionare preferably the polyolefin films such as polyethylene orpolypropylene though the polyamides or polyesters may also be used ifdesired. The film is transversely oriented and is oriented to asufficient degree so that it will readily form fibers, that is it isunilaterally oriented in the transverse direction to a relatively highdegree. The amount of orientation in order to provide for splitting ofthe film is well known in the art.

Referring to FIG. 1 a transversely oriented film I is mounted on a shaft11 mounted for rotation in bearings 12 mounted in suitable framing 13.The film passes through a pair of guide rollers 14 and 15 whichpreferably are driven by standard motors and pulleys. The guide rollersare mounted for rotation in bearings 16 mounted in the frame 17. Afterpassing through the guide rolls the film passes underneath a blade 18and onto the surface of a nonresilient roll 19. The nonresilient roll ismounted in bearings 20 mounted in the frame 17 and rotates in thedirection of the arrow shown. The blade is stationarily mounted from theframe 17 and preferably may be spring adjustable so as to be able tovary the pressure on the roll 19. Mounted adjacent the non-resilientroll is a resilient roll 21 which has its axis parallel to the axis ofthe non-resilient roll and by suitable pressure applying means 22 suchas air cylinders or hydraulic cylinders is in pressing contact with thenon-resilient roll. The resilient roll is also mounted for rotation inbearings 22 mounted in the frame 17. The non-resilient roll is driven bystandard motors and pulleys or other suitable drive means and may besuitable geared to the resilient roll to drive the resilient roll at thedesired speed or if desired the resilient roll may be separately driven.The rolls rotate in opposite directions as shown by their arrows and theresilient roll is rotated at a faster peripheral linear speed than thenonresilient roll. On passing through the nip the film is fibrillated orsplit into a network of fibers and is passed through a second set ofguide rolls 25 and 26 mounted for rotation in bearings 27 mounted in theframe 17. These rolls may also be driven. The split fiber is wound up ona standard wind-up mechanism 28.

As is more clearly shown in FIG. 2 the transversely oriented film 30 ispassed onto the surface of the non-resilient roll 31 by means of thestationary blade 32 which is in contact with the non-resilient rollalong a line parallel to the axis of the roll. This line of contact isimmediately adjacent the nip 33 formed by the non-resilient roll and theresilient roll 34. The blade is in pressing contact and is preferablyspring mounted to force the film onto the surface of the non-resilientroll so that the film takes the speed of the roll 31.

Immediately adjacent the stationary blade is the resilient roll 34 whichhas its axis parallel to the non-resilient roll and is in contacttherewith. Suitable loading means 35 such as pneumatic cylinders orhydraulic cylinders urge the resilient roll against the non-resilientroll at the desired pressure. The resilient roll is driven in thedirection of the arrow shown and is driven at a speed greater than theperipheral linear speed of the non-resilient roll. The pressing actionof the resilient roll and its increased speed applies compressive andlongitudinal forces to the film as it passes through the nip. Theseforces are placed over the entire width of the film and are placed oververy small incremental areas of the film as it passes between the nip touniformly and completely split or fibrillate the film into a web ofinterconnected fibers.

The non-resilient roll may be made of various types of materials, forexample, metal, hard plastics, etc. It is preferred that the surface befrictional such as knurled or sandblasted or some similar type of ofsurface to grip and hold the film so that the film maintains the speedof the non-resilient roll. The blade is preferably made of temperedsteel so that it may be pressed against the surface of the non-resilientroll and contact is made along the entire roll width. The resilient rollis preferably made of medium hard rubber or similar resilient materials,even plastic materials so that it may be urged against the non-resilientroll. In operation it is preferred that the resilient roll rotate atabout twice or more times the peripheral linear speed of thenon-resilient roll.

Although all of the various holders, pulleys, belts, and like mechanicalmeans, including suitable framing and pressure loading means, have notbeen illustrated completely in the drawings or described in thespecification for driving, pressing, or supporting the various rotatingrolls, at their desired or required speeds or with the rotation ormovement indicated by the direct arrows it is to be appreciated thatsuch elements have been omitted to keep the drawings and descriptiondistinct and to avoid the introduction of matters which are well knownexpedients in the art. The mechanical driving means, pressure means, andvarious frames which are used are conventional and merely involve theapplication of well known mechanical principles.

speed, simultaneously applying instantaneous compressive andlongitudinal forces across the width of the film while maintaining thespeed of the film at its given speed and removing the film from theapplication of said forces while maintaining the film at said givenspeed to split the film into a web of interconnected fibers.

1. A method of manufacturing a split fiber web from a transverselyoriented plastic film comprising: moving the transversely oriented filmin the direction of its length and at a given speed, simultaneouslyapplying instantaneous compressive and longitudinal forces across thewidth of the film while maintaining the speed of the film at its givenspeed and removing the film from the application of said forces whilemaintaining the film at said given speed to split the film into a web ofinterconnected fibers.